Process for making molds.



PATENTED NOV. 21, 1905.

M. KULLBR.

' PROCESS FOR. MAKING MOLDS.

APPLICATION FILED NOV. 21,1902.

NIT D STATES PATENT oFFIoE.

MAX KULLER, OF BUDAPEST, AUSTRIA-HUNGARY.

PROCESS, FOR MAKING nouns.

Specification of Letters Patent.

late nted' Nov. 21, 1905.

Application filed November 21,1902- Serial No. 132,806.

.To all whont it may concern: L

Be it known that I, MAx KULLER, a subject of the King of Prussia, German Emperor, and

a resident of Budapest, Empire of Austria- Hungary, have invented a certain new and useful Process for Making Molds, of which the following is a description.

- The object of the present invention is to pro duce a mold into which molten metal may be cast from models or patterns even of the most complicated nature with'recesses and undercuts without the employment of false core and without employing wax or elastic or flexibleintermediate models or patterns. This ob ject is obtained by mixing suitable ingredients with the mold-forming mass, which is plastered onto the model or pattern ina pasty co'nsistency, which ingredients impart to the said certain conditions.

mass the vproperty orcapability of becoming elastic or flexible for a certain'time and under This enables the mass which subsequently forms the mold to be removed from the model or pattern without, however, damaging or altering the impression obtained. The mass is subsequently rendered quite hard, retaining the impression even to the smallest details,and after having been dried forms the mold into which the metal is cast.

In carrying out the process the mass of which the mold 1s made.-suc'h, for instance,

as sand, infusorial earth, fire-clay, wood or coal dust, tow-waste, molasses, or the like-together with a suitable proportion of a binding medium-such as plaster-of-paris, resin, glycerin, dextrin, Arabic gum, or other suitable substance, or even without such addition is mixed up with a solution of an elastic materialsuch, for instance, as glue, gela-- tin, agar-agar, caoutchouc, gutta-percha,- or the l1kein a warm or cold condition. The

' pasty mass thus obtained is pasted in an even layer onto the model or pattern.

This mass Will become flexible ina short time, but remains sufliciently tough to enable it to be moved or pulled in any direction without breakingor'tearingr- The mass mayconsequently be stripped or carefully pulled off the model or pattern and subsequently become perfectly rigid or hard. This'subsequent hardening is due to the fact that the above-mentioned masssand,infusorial earth,

' or the like, with or without the addition'of resin or the likeis first held together by the elastic or flexible substance added and that the binding mediumfor instance, in the case of plaster-of-parisdoes not harden at once,

Q owing to thezefiect of the elastic substance on it, but only after. the elapse of some little time. If resin is employed as a binding medium, the same may be rendered eflective i. c., the hardening attained-by the application of heat.

It now substances are added to the fluid mass or coated onto the mass after it has attained its elastic state which are capableof rendering the elastic substances (glue, gelatin, and the like) insolublesuch, for instance, as alum, chromates, formalin the gelatin or the like cannot dissolve, and when "dried very strong molds, will be obtained from which the elastic substances may either be burned out (by glowing) or may be removed by suitable dissolving acids. By this means the necessary gas porosity 1s attained,

which may be increasedby adding suitable materialssuch as resin, tow-waste, coaldust,or the like-which will burn out when drying.

In the accompanying drawings, Figure 1 shows a model or pattern, such as a bust supported upon a suitable base. Fig. 2 shows the same pattern orbust partly covered by the material of which the mold is made, the

latter being surrounded by a sand bed heldwithin a mold-box. Fig. '3 shows bust completely covered bythe material of which the mold is made withthe inclosing sand bed and mold-box. Figs. 4 and 5 show the parts of turned over, and the hal-i of the same previously embedded is laid free and treated in exactly the same manner as that described. If

now the two parts (2 d of the mold-box are removed, the elastic flexible layers 0 0' will remain on the model. This flexible coating forming the actual mold may then be carefully taken or stripped off the model and each half then laid in its respective mold-box,

where it is allowed to-harden or caused to harden by heat or in anyother manner, ac-

cording to the ingredients employed in mak ing the mass as previously specified. In this burn or vaporize in the ordinary heat of the drying-furnace. The necessary porosity may be attained by suitable dissolving means or by employing acids, in which case the molds will be sufliciently pervious to render the casting of iron in the same possible.

According to one methodof producing the mold-forming mass about seventy-five grams of best gelatin are melted in about 1.56 liters of water slightly warmed. 1.4 kilograms of finely-sieved molders sand are then finely mixed with one kilogram of best plaster-ofparis, and this mixture is added to the gelatin solution above mentioned, the whole being gently stirred, the mass being then ready for use.

I claim as my invention 1. The hereindescribed process of produc ing molds for casting metals from amoldforming material having the quality, at successive stages, of taking an impression, of elasticity or flexibility permitting withdrawal withoutimpairing the impression and of har dening to receive molten metal, consisting in first applying the mold-forming material to the pattern or model; allowing the mass to set sufiiciently to secure a permanent impression; removing or stripping the mass while elastic from the pattern or model; allowing it to harden and finally imparting to it the nature of a sand mold by means of heat.

2. A process for producing molds for easting metals which consists in applying to the model or pattern a substance, possessing the property of becoming elastically flexible be fore it hardens, removing the said coating, while in its elastically-flexible state from the model or pattern, hardening the material and finally reducing it to a refractory sandy condition by heat. 4

3. A process for making molds for casting metals which consists in first applying to a model or pattern a mold-forming mass, consisting of a body material, an elastic element,

and a binding medium; allowing the mass to receive an impression of the model or pattern and assume the elastic condition; removing the mass from the model while in an elastic condition, subsequently hardehing the same and reducing it to the condition of a sand mold by heat; ln witness whereof I have hereunto set my hand in presence of two witnesses.

MAX KULLER. Witnesses:

FRANK Drmn (Innsrmc, NORMAN W. WILLEY. 

